Table 1. Baseline Demographic and Clinical Characteristicsa.
| Characteristics | Diet and exercise (n = 414) | Attention control (n = 409) |
|---|---|---|
| Age, mean (SD), y | 64.5 (7.8) | 64.7 (7.8) |
| Weight, mean (SD), kg | 100.7 (20.6) | 101.1 (22.0) |
| Height, mean (SD), m | 1.65 (0.09) | 1.66 (0.09) |
| Body mass index, mean (SD)b | 36.7 (6.5) | 36.9 (7.2) |
| Sex, No. (%) | ||
| Female | 320 (77.3) | 317 (77.5) |
| Male | 94 (22.7) | 92 (22.5) |
| Race, No. (%) | ||
| American Indian | 1 (0.2) | 1 (0.2) |
| Asian | 2 (0.5) | 1 (0.2) |
| Black | 111 (26.8) | 116 (28.4) |
| White | 289 (69.8) | 281 (68.7) |
| Other race or more than 1 racec | 11 (2.6) | 10 (2.4) |
| Hispanic ethnicity, No./total (%)d | 7/414 (1.7) | 3/404 (0.7) |
| Annual household income, $, No./total (%) | ||
| <20 000 | 54/395 (13.7) | 61/398 (15.3) |
| 20 000-34 999 | 64/395 (16.2) | 69/398 (17.3) |
| 35 000-49 999 | 67/395 (17.0) | 63/398 (15.8) |
| 50 000-74 999 | 93/395 (23.5) | 90/398 (22.6) |
| 75 000-99 999 | 52/395 (13.2) | 52/398 (13.1) |
| ≥100 000 | 65/395 (16.5) | 63/398 (15.8) |
| Education, No./total (%) | ||
| Less than high school | 13/412 (3.2) | 8/407 (2.0) |
| High school or equivalent | 47/412 (11.4) | 51/407 (12.5) |
| Some college | 164/412 (39.8) | 162/407 (39.8) |
| College degree | 115/412 (27.9) | 118/407 (29.0) |
| Graduate degree | 73/412 (17.7) | 68/407 (16.7) |
| Comorbid illnesse | ||
| Obesity (body mass index ≥30) | 365 (88) | 359 (88) |
| Hypertension | 276 (67) | 280 (69) |
| Arthritis in other joints | 229 (55) | 221 (54) |
| Diabetes | 74 (18) | 91 (22) |
| Cardiovascular disease | 43 (10) | 39 (10) |
| WOMAC score, mean (SD)f | ||
| Pain | 7.5 (3.2) | 7.5 (3.3) |
| Function | 26.0 (11.6) | 25.9 (12.0) |
eTable 1 in Supplement 2 contains the same categories restricted to patients for whom 18-month outcome data were available.
Calculated as weight in kilograms divided by height in meters squared.
Other categories included self-identified Egyptian (n = 1), Hispanic ethnicity with no race defined (n = 8), and Semitic (n = 1).
Reported on a self-administered demographics questionnaire.
Reported on a self-administered health history questionnaire as conditions diagnosed by a health care professional. With comorbid illnesses that could exclude patients from participation, final approval or denial for participation was provided after patient evaluation by a study physician.
The Western Ontario and McMaster Universities Osteoarthritic Index (WOMAC) consists of a self-administered questionnaire including 5 questions on pain and 17 questions on physical function. The scale for each question ranges from 0 (no symptoms) to 4 (extreme symptoms). Composite scores for pain range from 0 to 20 and for function from 0 to 68. Pain cut points on a 0- to 20-point scale are as follows: 2 to 8, mild; >8 to 14, moderate; and >14 to 20, severe (transformed from a 0- to 10-point scale reported in Kapstad et al23).